This family represents the N-terminal of the variant erythrocyte surface antigen 1, versions a and b, of Babesia. Babesia bovis is a tick-borne, intra-erythrocytic, protozoal parasite of cattle that shares many lifestyle parallels with the most virulent of the human malarial parasites, Plasmodium falciparum. Babesia uses antigenic variation to establish consistent infections of long duration. The two variants of VESA1, a and b, are expressed from different but closely related genes, and variation is achieved through the involvement of a segmental gene conversion mechanism and low-frequency epigenetic in situ switching of transcriptional activity from the VESA1 gene-pair to a possible other gene pair.

1: Antigenic variation in Babesia bovis occurs through segmental gene conversion of the ves multigene family, within a bidirectional locus of active transcription. Al-Khedery B, Allred DR; Mol Microbiol. 2006;59:402-414. PMID:16390438